Anchor for an implant assembly

ABSTRACT

A medical device includes an implant anchor comprising first and second opposing end portions. The implant anchor may also include a fixation element to configured to couple the implant anchor to an implant, and an anchor element configured to couple the implant anchor to bone. At least a portion of the implant anchor has a porous structure.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application Ser. No. 61/949,774, filed Mar. 7, 2014; U.S. Provisional Application Ser. No. 61/949,789, filed Mar. 7, 2014; U.S. Provisional Application Ser. No. 61/949,824, filed Mar. 7, 2014; and U.S. Provisional Application Ser. No. 61/950,762, filed Mar. 10, 2014, the entire disclosures of which are fully incorporated herein by reference.

FIELD

The present disclosure relates to devices and methods for the repair of defects that occur in cartilage on the surface of bone, as well as bone.

BACKGROUND

Articular cartilage, found at the ends of articulating bone in the body, is typically composed of hyaline cartilage, which has many unique properties that allow it to function effectively as a smooth and lubricious load-bearing surface. When injured, however, hyaline cartilage cells are not typically replaced by new hyaline cartilage cells. Healing is dependent upon the occurrence of bleeding from the underlying bone and formation of scar or reparative cartilage called fibrocartilage. While similar, fibrocartilage does not possess the same unique aspects of native hyaline cartilage and tends to be far less durable.

In certain instances, an injury may not be limited to the cartilage, but may also extend into the bone which supports the cartilage.

In some cases, it may be desirable or necessary to repair the damaged articular cartilage and/or bone using an implant. In instances where only cartilage may be damaged, the implant should have a shape substantially corresponding to the articular cartilage proximate the area where the implant is to be placed in order to maximize the patient's comfort, minimize damage to surrounding areas, and maximize the functional life of the implant. In instances where bone is damaged, the implant may be increased in size to accommodate the damaged location.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of the claimed subject matter will be apparent from the following detailed description of some example embodiments consistent therewith, which description should be considered with reference to the accompanying drawings, wherein:

FIG. 1 is a fragmentary side view of a knee having therein an exemplary implant assembly comprising an implant and anchor according to one embodiment of the present disclosure;

FIG. 2 is an exploded perspective view of the implant and the anchor of FIG. 1;

FIG. 3 is a close up cross-sectional side view of the anchor of FIG. 1; and

FIG. 4 is a side view of an alternative anchor according to the present disclosure;

DETAILED DESCRIPTION

It may be appreciated that the present disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the drawings. The invention(s) herein may be capable of other embodiments and of being practiced or being carried out in various ways. Also, it may be appreciated that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting as such may be understood by one of skill in the art.

The present disclosure provides an anchor and corresponding implant which may be used as an assembly for the repair of defects that occur in cartilage on the surface of bone, as well as bone itself. The anchor and corresponding implant may be used in any suitable location of a body, particularly a human body. In certain embodiments, the implant may be a cartilaginous joint or a synovial joint implant assembly.

Exemplary cartilaginous joints may include the joints formed between the intervertebral discs of the spinal column. Exemplary synovial joints may include ball-and-socket joints (e.g. hip joints, shoulder (glenohumeral) joints); hinge or modified hinge joints (e.g. knee joints, elbow joints); condyloid joints (e.g. wrist joint); gliding joints (e.g. acromioclavicular joints); and saddle joints (e.g. sternoclavicular joint, carpometacarpal joint)

In various embodiments, the implant assembly may be formed from a plurality of two or more components. In such instance, a connection is formed between the components to inhibit separation and/or rotation of the components relative to one another. The connection formed between the components may particularly be a frictional connection and/or a mechanical connection.

Mechanical connections formed between the components herein may include friction fit connections (which may also be referred to an interference or press fit) and positive mechanical engagement connections. A friction fit connection may be understood as a connection formed between the components which solely relies upon friction to inhibit separation of the components, particularly by one of the components being pressed into the other component such that at least one of the components is compressed (deformed) against one another. On the other hand, a positive mechanical engagement connection may be understood as a connection formed between the components which does not rely solely on friction to inhibit separation of the components and which includes a mechanical interlock to inhibit separation of the components (e.g. overlapping surfaces).

For the implant assemblies herein, in certain applications, a friction fit connection between the components may offer certain advantages over a positive mechanical engagement, such as where it is particularly desirable to inhibit rotation of the components relative to one another. In other applications, a positive mechanical engagement connection between the components may offer certain advantages over a friction fit connection, such as where it is particularly desirable to inhibit separation of the components relative to one another. In still other applications both a friction fit connection and a positive mechanical engagement connection may be particularly desirable to inhibit rotation and separation of the components relative to one another, respectively.

According to certain embodiments, the implant assembly may replace only a portion of the articular surface proximate the defect site rather than the entire articular surface. As such, the implant assembly may minimize the amount of the articular surface which is operated on thus allowing more of the patient's original articular surface to be unaffected and providing a more physiologically normal joint. However, in other embodiments, the implant assembly may replace the entire articular surface. In still other embodiments, the implant assembly may replace the portion of the bone adjacent (outside) the articular surface.

Depending on the size of the implant assembly, such may allow for minimally invasive surgery, particularly laparoscopic surgery (which may also be referred to as keyhole surgery), which may reduce the amount of pain and/or discomfort experienced by the patient and may reduce healing times. However, while in certain embodiments the implant assembly may be configured to replace only a portion of the articular surface proximate the defect site rather than the entire articular surface, in other embodiments the implant assembly may be configured to replace the entire articular surface.

Referring now to FIG. 1, there is shown an implant assembly/system 10 according to the present disclosure inserted into bone 2, and more particularly forming a surface of a joint 4. Implant assembly 10 comprises an implant 20 and an elongated first anchor 30.

Implant 20 may be formed of a plastic composition and may more particularly comprise, essentially consist of, or consist of a plastic composition. Exemplary plastic compositions may comprise thermoplastic compositions such as polyether ether ketone (PEEK) and polyethylene (PE), including ultrahigh molecular weight polyethylene (UHMWPE) and high density polyethylene (HDPE). In other embodiments, implant body 22 may be formed of a metal composition and may more particularly comprise, essentially consist of, or consist of a metal composition. Exemplary metal compositions may comprise stainless steel, titanium, aluminum, chromium cobalt, and/or any alloy thereof.

Implant 20 has a joint facing side including a load bearing (joint articulation) surface 22. The load bearing surface 22 may have a contour substantially corresponding to or based on the contour of an articular surface of a patient being repaired. The contour of the load bearing surface 22 may be based on a plurality of measurements taken at the patient's articular surface (for example, using a measuring and/or mapping tool as generally described in U.S. Pat. Nos. 6,520,964, 6,610,067, 6,679,917, 7,029,479 and 7,510,558, which are fully incorporated herein by reference) and/or may be based on one or more templates.

The load bearing surface 22 may be based on two or more curvatures, for example, the anterior-posterior curvature and the superior-inferior curvature. One or more of the anterior-posterior and/or superior-inferior curvatures may themselves be based on multiple curves, (for example, as generally described in U.S. patent application Ser. No. 12/027,121, filed Feb. 6, 2008 and entitled System and Method for Joint Resurface Repair, which is fully incorporated herein by reference).

While the load bearing surface 22 is illustrated having a generally convex contour, it should be appreciated that the load bearing surface 22 is not limited to this configuration and will depend on the intend application. For example, the load bearing surface 22 may include, but is not limited to, concave configurations and/or generally hemi-spherical shapes.

With reference to FIG. 2, implant 20 comprises a bone facing surface 26, which may substantially correspond to a contour of an excision site formed in an articular surface of a patient. More particularly, a perimeter of the implant 20 may substantially corresponds to a perimeter of an excision site formed in the articular surface.

Bone facing surface 26 includes a first fixation element 32. First fixation element 32 comprises a fixation recess 34 formed in a fixation base 36 of implant 20. As shown, fixation recess 34 is substantially cylindrical and may be centered around a longitudinal axis LA of the anchor 30. More particularly, the sidewall 41 of fixation recess 34 is tapered.

It should be appreciated that the implant assembly/system 10 illustrated with respect to FIGS. 1 and 2 is provided for illustrative purposes, and that the anchor 30 may be used with any implant 20 (for example, but not limited to, an implant as described in U.S. Provisional Application Ser. Nos. 61/949,774; 61/949,789; 61/949,824; and/or 61/950,762 and/or in U.S. Pat. Nos. 6,520,964, 6,610,067, 6,679,917, and 7,678,151, all of which are fully incorporated herein by reference).

Turning to FIG. 3, the anchor 30 is configured to engage and/or secure the implant assembly 20 to the patient's bone. Anchor 30 includes a proximal and a distal end region. Additionally, the anchor 18 may optionally include a passageway 40, for example, a longitudinal passageway, configured to be advanced over a guide wire (not shown) as generally described in U.S. Pat. Nos. 6,520,964, 6,610,067, 6,679,917, 7,678,151, 7,896,883, 8,177,841, and 8,388,624, as well as U.S. Publication No. 2010/0368238, all of which are fully incorporated herein by reference. The use of a cannulated passageway 40 and the guide wire may facilitate alignment of the anchor 30 with respect to the excision site and the surrounding articular surface. For example, the anchor 18 may be inserted into bone 14 or may be inserted into a shaft drilled in the bone 14 to reduce risks or complications arising from the insertion of the anchor 18. Without limitation, a pilot hole may be formed in the bone 14 for receiving the anchor 18 prior to installing the anchor 18. A diameter of the pilot hole may be smaller than the anchor 18, although example embodiments may vary and are not limited thereto.

The proximal end region of the anchor 30 includes a second fixation element 44 configured to form a connection with the first fixation element 32. As shown by the figures, anchor 30 may comprise a screw with a fully or partially threaded tapered or non-tapered cylindrical shank which is arranged substantially transverse to the overlying portion of the load bearing surface 22.

As discussed herein, second fixation element 44 is configured to engage with the first fixation element 32 to form a connection therebetween. In the illustrated embodiment, the second fixation element 44 includes a tapered (male) protrusion. The tapered protrusion includes a tapered sidewall 50 configured to contact and abut against at least a portion of a tapered sidewall 41 of the first fixation element 32 to form a frictional connection therebetween.

It should be appreciated that while the first and second fixation elements 32, 44 are generally illustrated as a recess and a protrusion, respectively, the implant system 10 consistent with the present disclosure is not limited to this arrangement unless specifically claimed as such. For example, the first and second fixation elements 32, 44 may include a protrusion and a recess, respectively, as well as other embodiments such as, but not limited to, one or more of the fixation elements described in any one of the references incorporated by reference (e.g., without limitation, a snap-fit arrangement).

The proximal end region of the anchor 30 may also include a driver receptacle 52 arranged to receive a drive member therein, particularly to drive the first anchor 30 into bone. For example, driver receptacle 52 may be arranged to receive a drive member (not shown) to cause one or more anchor elements 56 of the first anchor 30 to engage the bone. The driver receptacle 52 may allow torque to be transmitted to the anchor 30 to rotate the anchor 30 such that one or more external screw (helical) threads 58 threadably engage and connect with the bone.

Elongated anchor 30 may be formed of a plastic composition and may more particularly comprise, essentially consist of, or consist of a plastic composition. Exemplary plastic compositions may comprise thermoplastic compositions such as polyether ether ketone (PEEK) and polyethylene (PE) such as ultrahigh molecular weight polyethylene (UHMWPE) and high density polyethylene (HDPE). In other embodiments, anchor 32 may be formed of a metal composition and may more particularly comprise, essentially consist of, or consist of a metal composition. Exemplary metal compositions may comprise stainless steel, titanium, aluminum, chromium cobalt, and/or any alloy thereof.

As best shown by FIG. 3, anchor 30 has a second fixation element 44 which is non-porous solid structure and a distal end anchor portion 48 which is a porous solid structure, which has a skeletal (scaffold) framework which defines a plurality of interstices (pores). The porous structure may encourage bone growth into the interstices thereof to better secure the anchor 30 to the bone.

The skeletal framework and interstices may be arranged randomly or may be arranged in an orderly geometric pattern of repeating unit cells (e.g. dodecahedron), with the struts of the framework and the interstices repeating in size and shape. The struts of the framework may have a thickness in a range of 150 μm to 300 μm (e.g. 230 μm), and the interstices may have a size (diameter) in a range of 240 μm to 730 μm (e.g. 490 μm). The porosity of the porous structure may be in a range of 55% to 75% (e.g. 68%). In certain embodiments, the interstices may extend completely through the structure or may extend partially through the structure.

In certain embodiments, the skeletal framework and interstices may be provided by a three-dimensional, multi-layered mesh or lattice structure. For example, the skeletal framework and interstices may comprise a frameworks produced using computer controlled Selective Laser Powder Processing techniques (SLPP). Selective Laser Powder Processing (SLPP) may be understood as a layer-wise manufacturing technique that allows generating complex three dimensional parts by selectively consolidating successive layers of powder material on top of each other using thermal energy supplied by a focused laser beam. SLPP may include the processing of various types of powder with different types of material (plastic, metal, ceramic) and powder composition (e.g. single component powder grains, composite powder grains, mixture of powder grains). Different binding mechanisms may be responsible for the consolidating of the powder: solid state sintering, chemically induced binding, liquid phase sintering, partial melting and full melting. The thermal energy supplied by the laser beam may be added to the powder in a second step after the deposition of a powder layer in the first step, or the deposition and consolidating of the powder can be combined in a single step.

Selective Laser Powder Processing comprises amongst other the following techniques: selective laser sintering (SLS), selective laser full melting (SLFM) and laser cladding. An overview of Selective Laser Powder Processing techniques is presented in J. P. Kruth, et al., Binding mechanisms in selective laser sintering and selective laser melting, Proceedings of 15th annual Solid Freeform Fabrication Symposium, Austin, Aug. 2-4, 2004.

In other embodiments the skeletal framework and interstices may be provided by a cellular foam material including a plurality of isolated or interconnected cellular pores. Such may include cellular foam plastics and cellular foam metals.

Referring now to FIG. 4, the anchor elements 56, and more particularly the external screw (helical) threads 58 of the distal end anchor portion 48, are also formed of a non-porous solid structure along with the second fixation element 44. In such case, the shank root or (shank root diameter) 64 remains as a porous solid structure.

According to one aspect, the present disclosure may feature a medical device. The medical device may include an implant anchor comprising first and second opposing end portions. The implant anchor may also include a fixation element to configured to couple the implant anchor to an implant, and an anchor element configured to couple the implant anchor to bone. At least a portion of the implant anchor has a porous structure.

According to another aspect, the present disclosure may feature a medical device comprising and implant and an implant anchor. The implant may include a load bearing surface, a bone facing surface, and a first fixation element. The implant anchor may comprise first and second opposing end portions, a second fixation element to configured to engage the first fixation element to couple the implant anchor to an implant, and an anchor element configured to couple the implant anchor to bone. At least a portion of the implant anchor has a porous structure.

According to yet another aspect, the present disclosure may feature a medical device comprising an implant anchor. The implant anchor may include a first and a second opposing end portion, wherein the first end portion of the implant anchor comprises a fixation element to connect the implant anchor to an implant. The second end portion of the implant anchor may have a porous structure to connect the anchor to bone. According to yet a further aspect, the present disclosure may feature a threaded shank having a screw thread, wherein at least a portion of the screw thread has a porous structure.

Throughout the present description, like reference numerals and letters indicate corresponding structure throughout the several views, and such corresponding structure need not be separately discussed. Furthermore, any particular feature(s) of a particular exemplary embodiment may be equally applied to any other exemplary embodiment(s) of this disclosure as suitable. In other words, features between the various exemplary embodiments described herein are interchangeable as suitable, and not exclusive.

While a preferred embodiment of the present invention(s) has been described, it should be understood that various changes, adaptations and modifications can be made therein without departing from the spirit of the invention(s) and the scope of the appended claims. The scope of the invention(s) should, therefore, be determined not with reference to the above description, but instead should be determined with reference to the appended claims along with their full scope of equivalents. Furthermore, it should be understood that the appended claims do not necessarily comprise the broadest scope of the invention(s) which the applicant is entitled to claim, or the only manner(s) in which the invention(s) may be claimed, or that all recited features are necessary. 

What is claimed is:
 1. A medical device, comprising: an implant anchor comprising first and second opposing end portions, said implant anchor further comprising: a fixation element to configured to couple said implant anchor to an implant; and an anchor element comprising a threaded shank configured to couple said implant anchor to bone, said threaded shank comprising a screw thread; wherein at least a portion of said screw thread has a porous structure.
 2. The medical device of claim 1, wherein: said fixation element has a non-porous-structure.
 3. The medical device of claim 1, wherein: said second end portion of said implant anchor comprises said anchor element.
 4. The medical device of claim 1, wherein: at least a portion of said threaded shank is formed by said porous structure.
 5. The medical device of claim 4, wherein: a portion of said screw thread is formed by a non-porous structure.
 6. The medical device of claim 4, wherein: said threaded shank of said implant anchor comprises a shank root; and at least a portion of said shank root is formed by said porous structure.
 7. The medical device of claim 1, wherein: said porous structure is formed by metal particles.
 8. The medical device of claim 1, wherein: said porous structure is formed by a plurality of layers of metal particles.
 9. The medical device of claim 8, wherein: said metal particles comprise metal powder.
 10. The medical device of claim 1, wherein: said porous structure comprises a skeletal framework and a plurality of interstices arranged in an orderly geometric pattern of repeating unit cells.
 11. The medical device of claim 10, wherein: said repeating cell unit is a dodecahedron.
 12. The medical device of claim 10, wherein: said skeletal framework is formed by a plurality of struts; and said struts have a thickness in a range of 150 μm to 300 μm.
 13. The medical device of claim 10, wherein: said interstices have a size in a range of 240 μm to 730 μm.
 14. The medical device of claim 10, wherein: said porous structure has a porosity in a range of 55% to 75%.
 15. The medical device of claim 10, wherein: said porous structure comprises a plurality of layers.
 16. The medical device of claim 15, wherein: said plurality of layers form a three-dimensional, multi-layered mesh or lattice structure.
 17. The medical device of claim 10, wherein: said porous structure forms at least a portion of a threaded shank.
 18. The medical device of claim 17, wherein: said porous structure forms a shank root of said threaded shank.
 19. The medical device of claim 1, further comprising an implant configured to be coupled said implant anchor.
 20. The medical device of claim 19, wherein said implant includes a load bearing surface, a bone facing surface, and a fixation element configured to be coupled to said fixation element of said implant anchor.
 21. The medical device of claim 20, wherein said fixation elements of said implant and said implant anchor include mating tapered surfaces configured to form a frictional connection therebetween.
 22. The medical device of claim 1, wherein said implant anchor includes a longitudinally disposed passageway extending between said first and said second opposing end portions.
 23. A medical device, comprising: an implant including a load bearing surface, a bone facing surface, and a first fixation element; and an implant anchor comprising first and second opposing end portions, said implant anchor further comprising: a second fixation element to configured to engage said first fixation element to couple said implant anchor to an implant; and an anchor element comprising a screw thread having configured to couple said implant anchor to bone; wherein at least a portion of said screw thread has a porous structure.
 24. The medical device of claim 23, wherein said implant anchor includes a longitudinally disposed passageway.
 25. A medical device, comprising: an implant anchor, wherein said implant anchor comprises first and second opposing end portions; wherein said first end portion of said implant anchor comprises a fixation element to connect said implant anchor to an implant; and wherein said second end portion of said implant anchor comprises a screw thread having a porous structure to connect said anchor to bone.
 26. The medical device of claim 25, wherein said implant anchor includes a longitudinally disposed passageway extending between said first and said second opposing end portions. 